the sum of the first 100 counting numbers is 100(101)/2=5050. if we multiply each of first 100 counting numbers by 2, we get the first 100 even numbers(2,4,6...198,200). so the sum of the first 100 even numbers is 5050(2) = 10100

the sum of the first 200 counting numbers is n=200; n(n+1)/2 = 20100.

subtract from this the sum of the first 100 even numbers, we will be left with the sum of the first 100 odd numbers or:

20100 - 10100 = 10000

include<stdio.h>

int main() {

int i,z=0,c=1;

for(i=1;i<200;i++)
    if(i%2 !=0)
    {
        printf("%d ",c);            
        printf("%d\n",i);
        z=z+i;
        c++;
    }

    printf("%d\n",z);

}

run this prongram in c.